A fingerprint identification circuit, a compensation method, a display panel and a display device

Abstract

The application discloses a kind of fingerprint identification circuit, compensation method, display panel and display device, the fingerprint identification circuit includes: reset unit, photosensitive unit, driving unit, switching unit and compensation control unit;Reset unit is connected between first signal end and first node;Photosensitive unit is connected between second signal end and first node;Driving unit is connected between third signal end and second node, and its control end is connected first node;Switching unit is connected between second node and signal output end;The output end of compensation control unit is connected first signal end, third signal end or signal output end;In brightness compensation stage, the output end of compensation control unit provides first electric signal, and at least two frames of scanning picture are provided with different first electric signal;In non-compensation stage, the output end of compensation control unit provides second electric signal.In the present application, compensation control unit can adjust the size of fingerprint identification signal, improve imaging quality.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fingerprint identification, and in particular to a fingerprint identification circuit, a compensation method, a display panel and a display device. BACKGROUND

[0002] With the progress and development of science and technology, the improvement of people's living standards, the use of display panels has penetrated into various electronic products. With the rapid development of display panels, more auxiliary functions are integrated into display panels, enriching the functions of electronic products. For example, a large number of display panels have applied fingerprint identification functions.

[0003] At present, the display panel integrates the fingerprint identification function, and the fingerprint identification is performed to form a fingerprint image. However, the current fingerprint imaging quality of the display panel needs to be improved. SUMMARY

[0004] The present application provides a fingerprint identification circuit, a compensation method, a display panel and a display device to improve the fingerprint imaging quality.

[0005] According to an aspect of the present application, a fingerprint identification circuit is provided, comprising: a reset unit, a photosensitive unit, a driving unit, a switching unit and a compensation control unit;

[0006] The reset unit is connected between a first signal end and a first node, and a control end of the reset unit is connected to a reset control end;

[0007] The photosensitive unit is connected between a second signal end and the first node, and is configured to sense a light signal and generate a corresponding electrical signal;

[0008] The driving unit is connected between a third signal end and a second node, and a control end of the driving unit is connected to the first node;

[0009] The switching unit is connected between the second node and a signal output end, and a control end of the switching unit is connected to a switching control end;

[0010] An output end of the compensation control unit is connected to a signal adjusting end, and the signal adjusting end is the first signal end, the third signal end or the signal output end;

[0011] In a fingerprint identification stage, the fingerprint identification circuit works; the fingerprint identification stage includes multiple frames of scanning pictures, and the fingerprint identification stage includes a brightness compensation stage and a non-compensation stage, the brightness compensation stage includes at least one frame of scanning picture, and the non-compensation stage includes at least one frame of scanning picture;

[0012] In the brightness compensation stage, the output end of the compensation control unit provides a first electrical signal, and at least two frames of scanning pictures are provided with different first electrical signals;

[0013] In the non-compensation phase, the output end of the compensation control unit provides a second electrical signal.

[0014] According to another aspect of the present application, there is provided a compensation method applied in the fingerprint identification circuit as described above, the compensation method comprising:

[0015] detecting whether the time difference between the starting time of the current frame of scanning picture and the starting time of the previous frame of scanning picture is greater than a first scanning time length;

[0016] if yes, entering a brightness compensation phase, in which the output end of the compensation control unit is controlled to provide a first electrical signal, and at least two frames of scanning picture are provided with different first electrical signals.

[0017] According to another aspect of the present application, there is provided a display panel comprising the fingerprint identification circuit as described above.

[0018] According to another aspect of the present application, there is provided a display device comprising the display panel as described above.

[0019] In the embodiments of the present application, the fingerprint identification circuit comprises a compensation control unit, the output end of the compensation control unit is connected to a signal adjusting end, the signal adjusting end is a first signal end, a third signal end or a signal output end; the fingerprint identification phase comprises a brightness compensation phase and a non-compensation phase; in the brightness compensation phase, the output end of the compensation control unit provides a first electrical signal, and at least two frames of scanning picture are provided with different first electrical signals; in the non-compensation phase, the output end of the compensation control unit provides a second electrical signal. The compensation control unit provides different first electrical signals to the signal adjusting end in the brightness compensation phase, which can adaptively adjust the size of the fingerprint identification signal of the fingerprint identification circuit, and further realize brightness adjustment of the sub-frame picture formed in the brightness compensation phase, reduce the brightness difference between the sub-frame picture formed in the brightness compensation phase and the sub-frame picture formed in the non-compensation phase, make the brightness of each sub-frame picture in the fingerprint identification phase tend to be consistent, and improve the imaging quality and the fingerprint identification precision.

[0020] It should be understood that the description in this section is not intended to identify key or critical features of the embodiments of the present application or to limit the scope of the present application. Other features of the present application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort.

[0022] Figure 1 is a schematic diagram of a fingerprint identification circuit provided by an embodiment of the present application;

[0023] Figure 2 is a schematic diagram of a display panel provided by an embodiment of the present application;

[0024] Figure 3 is a schematic diagram of another fingerprint identification circuit provided by an embodiment of the present application;

[0025] Figure 4 is a schematic diagram of still another fingerprint identification circuit provided by an embodiment of the present application;

[0026] Figure 5 is a schematic diagram of still another fingerprint identification circuit provided by an embodiment of the present application;

[0027] Figure 6 is a schematic diagram of still another fingerprint identification circuit provided by an embodiment of the present application; Figure 5 is a timing diagram of the fingerprint identification circuit shown in FIG. 8;

[0028] Figure 7 is a schematic diagram of still another fingerprint identification circuit provided by an embodiment of the present application;

[0029] Figure 8 is a schematic diagram of still another fingerprint identification circuit provided by an embodiment of the present application;

[0030] Figure 9 is a schematic diagram of still another fingerprint identification circuit provided by an embodiment of the present application;

[0031] Figure 10 is a schematic diagram of a compensation method provided by an embodiment of the present application;

[0032] Figure 11 is a timing diagram of the fingerprint identification circuit shown in FIG. 8; Figure 8 is another timing diagram of the fingerprint identification circuit shown in FIG. 8;

[0033] Figure 12 is a schematic diagram of a display device provided by an embodiment of the present application. Figure 8 is another timing diagram of the fingerprint identification circuit shown in FIG. 8;

[0034] Figure 13 is a schematic diagram of a display device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0035] In the following, the technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort should fall within the protection scope of the present application.

[0036] It should be noted that the terms "first", "second" and the like in the description and claims of the present application and the above drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in other than the order illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a list of steps or units need not be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to such processes, methods, products or devices.

[0037] Figure 1 is a schematic diagram of a fingerprint identification circuit provided by an embodiment of the present application. In the embodiment, the fingerprint identification circuit includes a reset unit 11, a photosensitive unit 12, a driving unit 13, a switching unit 14 and a compensation control unit 15; the reset unit 11 is connected between a first signal end V1 and a first node N1, and a control end of the reset unit 11 is connected to a reset control end C1; the photosensitive unit 12 is connected between a second signal end V2 and the first node N1, and is configured to sense a light signal and generate a corresponding electrical signal; the driving unit 13 is connected between a third signal end V3 and a second node N2, and a control end of the driving unit 13 is connected to the first node N1; the switching unit 14 is connected between the second node N2 and a signal output end OUT, and a control end of the switching unit 14 is connected to a switching control end C2; an output end of the compensation control unit 15 is connected to a signal adjustment end, and the signal adjustment end is the first signal end V1, the third signal end V3 or the signal output end OUT; in a fingerprint identification phase, the fingerprint identification circuit works; the fingerprint identification phase includes multiple frames of scanning pictures, and the fingerprint identification phase includes a brightness compensation phase and a non-compensation phase, the brightness compensation phase includes at least one frame of scanning picture, and the non-compensation phase includes at least one frame of scanning picture; in the brightness compensation phase, the output end of the compensation control unit 15 provides a first electrical signal, and different first electrical signals are provided for at least two frames of scanning pictures; in the non-compensation phase, the output end of the compensation control unit 15 provides a second electrical signal. Figure 1As shown, the optional signal conditioning end is the first signal end V1. In this embodiment, the signal conditioning end is taken as the first signal end V1 as an example, and the structure and working process of the fingerprint identification circuit are described in detail. In subsequent other embodiments, the optional signal conditioning end is the third signal end V3, or the optional signal conditioning end is the signal output end OUT, and the structure and working process of different fingerprint identification circuits will be described in the corresponding embodiments below. This embodiment will not be described in detail.

[0038] In this embodiment, the fingerprint identification circuit includes a reset unit 11 connected between the first signal end V1 and the first node N1, and the control end of the reset unit 11 is connected to the reset control end C1. The reset control end C1 provides a reset control signal with high and low levels alternately, which controls the reset unit 11 to be turned on or turned off. For example, the reset control end C1 provides a high-level signal to control the reset unit 11 to be turned on, and the reset control end C1 provides a low-level signal to control the reset unit 11 to be turned off; or the reset control end C1 provides a low-level signal to control the reset unit 11 to be turned on, and the reset control end C1 provides a high-level signal to control the reset unit 11 to be turned off. When the reset control end C1 controls the reset unit 11 to be turned on, the signal provided by the first signal end V1 is written to the first node N1, and the reset of the first node N1 is realized.

[0039] The fingerprint identification circuit includes a light sensing unit 12 connected between the second signal end V2 and the first node N1, which is used to sense the light signal and generate a corresponding electrical signal. The optional light sensing unit 12 is a photosensitive diode, the first pole of which is connected to the second signal end V2 and the second pole of which is connected to the first node N1; for example, the first pole of the photosensitive diode is the anode and the second pole is the cathode; but the structure of the light sensing unit is not limited to the photosensitive diode. When the fingerprint identification circuit works, the second signal end V2 provides a fixed voltage signal Vcom, the light sensing unit 12 senses the light signal and converts the light signal into an electrical signal, thereby affecting the potential of the first node N1. The potential of the first node N1 is affected by the on-off state of the reset unit 11 and the sensed light signal of the light sensing unit 12, and the potential of the first node N1 can represent the strength of the light signal.

[0040] The fingerprint identification circuit comprises a driving unit 13 connected between the third signal terminal V3 and the second node N2, and a control terminal of the driving unit 13 is connected to the first node N1. The potential of the first node N1 changes between high and low levels to control the driving unit 13 to be turned on or turned off. For example, the high-level potential of the first node N1 turns on the driving unit 13, and the low-level potential of the first node N1 turns off the driving unit 13; or the low-level potential of the first node N1 turns on the driving unit 13, and the high-level potential of the first node N1 turns off the driving unit 13. When the driving unit 13 is turned on by the potential of the first node N1, the driving unit 13 generates a corresponding leakage current according to the signal provided by the third signal terminal V3, and the leakage current is transmitted to the second node N2.

[0041] The fingerprint identification circuit comprises a switching unit 14 connected between the second node N2 and the signal output terminal OUT, and a control terminal of the switching unit 14 is connected to the switching control terminal C2. The switching control terminal C2 provides a switching control signal with high and low levels alternately to control the switching unit 14 to be turned on or turned off. For example, the high-level signal provided by the switching control terminal C2 turns on the switching unit 14, and the low-level signal provided by the switching control terminal C2 turns off the switching unit 14; or the low-level signal provided by the switching control terminal C2 turns on the switching unit 14, and the high-level signal provided by the switching control terminal C2 turns off the switching unit 14. When the switching unit 14 is turned on by the switching control terminal C2, the leakage current of the second node N2 flows through the switching unit 14 and is output through the signal output terminal OUT.

[0042] The electrical signal output by the signal output terminal OUT is the fingerprint identification signal generated by the fingerprint identification circuit in response to the sensed optical signal, and the fingerprint identification module identifies the fingerprint information according to the fingerprint identification signals output by the fingerprint identification circuits.

[0043] The fingerprint identification circuit includes a compensation control unit 15, and an output end of the compensation control unit 15 is connected to the signal adjusting end. In this embodiment, the signal adjusting end is taken as the first signal end V1 for example, that is, the output end of the compensation control unit 15 is connected to the first signal end V1. The output end of the compensation control unit 15 provides the first electric signal or the second electric signal to the signal adjusting end, and the fingerprint identification stage includes multiple frames of scanning pictures. In different frames of scanning pictures, the electric signal provided by the output end of the compensation control unit 15 to the signal adjusting end can be different. Specifically, in the fingerprint identification stage, the fingerprint identification circuit works; the fingerprint identification stage includes multiple frames of scanning pictures, and the fingerprint identification stage includes a brightness compensation stage and a non-compensation stage, the brightness compensation stage includes at least one frame of scanning picture, and the non-compensation stage includes at least one frame of scanning picture; in the brightness compensation stage, the output end of the compensation control unit 15 provides the first electric signal, and different first electric signals are provided to at least two frames of scanning pictures; in the non-compensation stage, the output end of the compensation control unit 15 provides the second electric signal. Here, the output end of the compensation control unit 15 providing the electric signal to one frame of scanning picture substantially means that the output end of the compensation control unit 15 provides the electric signal to the signal adjusting end within one frame of scanning duration.

[0044] At present, a fingerprint identification module is integrated in a display panel, and the fingerprint identification module has a fingerprint identification function, so that the display panel has the fingerprint identification function. Figure 2 is a schematic diagram of a display panel provided by an embodiment of the present application, as Figure 2 shown, the display panel includes a fingerprint identification module (not shown), and the fingerprint identification module includes a plurality of fingerprint identification circuits 16. The areas where the plurality of fingerprint identification circuits 16 are distributed constitute a fingerprint identification area 10 of the display panel, and the plurality of fingerprint identification circuits 16 in the fingerprint identification area 10 can be arranged in an array, but are not limited thereto. It can be understood that the fingerprint identification module further includes other auxiliary structures, and the other auxiliary structures are connected and matched with the fingerprint identification circuits 16 to enable the display panel to have the fingerprint identification function. The fingerprint identification circuits 16 in the display panel can be distributed in a local area of the display area, and then the fingerprint identification area 10 is located in the local area of the display area, so that full-screen display and local fingerprint identification are realized. In other embodiments, the fingerprint identification circuits in the display panel can be distributed in the entire area of the display area, and then the fingerprint identification area overlaps the entire area of the display area, so that full-screen display and full-screen fingerprint identification are realized.

[0045] In the fingerprint recognition stage, the fingerprint recognition module works, and the fingerprint recognition circuit outputs a fingerprint recognition signal. The fingerprint recognition stage includes multiple frames of scanning pictures. In one frame of scanning picture, each row of fingerprint recognition circuits 16 in the fingerprint recognition area 10 outputs a fingerprint recognition signal. For example, the fingerprint recognition area 10 scans in a line-by-line scanning manner. In this case, one frame of scanning picture refers to that the fingerprint recognition signal is output from the first row of fingerprint recognition circuits 16, and then the scanning is performed row by row until the fingerprint recognition signal is output from the last row of fingerprint recognition circuits 16. In this case, one scanning period of the first row to the last row of the fingerprint recognition area 10 is defined as one frame of scanning picture. In other embodiments, the fingerprint recognition area can scan in an interlaced scanning manner. In this case, the fingerprint recognition signal is output from each odd row of fingerprint recognition circuits row by row, and then the fingerprint recognition signal is output from each even row of fingerprint recognition circuits row by row. In this case, one scanning period of the first row to the last row of the fingerprint recognition area is defined as one frame of scanning picture. In one frame of scanning picture, the fingerprint recognition module performs fingerprint recognition according to the fingerprint recognition signals output by each fingerprint recognition circuit, and a sub-frame picture is formed. In the fingerprint recognition stage, multiple frames of scanning pictures are included. In this case, the fingerprint recognition module forms a fingerprint image according to multiple sub-frame pictures.

[0046] The fingerprint recognition stage is composed of multiple frames of scanning pictures. In a theoretical case, the scanning frequency is fixed in the fingerprint recognition stage, and the time interval of the first row scanning of adjacent two frames of scanning pictures is fixed or close. If the time interval of the first row scanning of the current frame of scanning picture and the first row scanning of the previous frame of scanning picture is too large, for example, the time interval is at least two scanning time lengths of the frame of scanning picture, the end time of the last row scanning of the previous frame of scanning picture is defined as the end time of the previous fingerprint recognition stage, and the start time of the first row scanning of the current frame of scanning picture is defined as the start time of the new fingerprint recognition stage.

[0047] It is found through detection of the existing fingerprint imaging that, in the fingerprint recognition stage, the brightness of the first frame of picture is relatively large, and the brightness of the picture decreases with the increase of the frame number until reaching a stable state. Research shows that the reasons for causing this phenomenon can include at least one of the following cases: 1) there is a parasitic capacitor in the fingerprint recognition circuit, and the influence of the parasitic capacitor decreases with the increase of the frame number. Therefore, the fingerprint recognition signal value of the first few frames of picture in the fingerprint recognition stage is relatively high, so that the brightness of the first few frames of picture is relatively large; 2) there is a leakage in the fingerprint recognition circuit or between different fingerprint recognition circuits, and the influence of the leakage decreases with the increase of the frame number. Therefore, the fingerprint recognition signal value of the first few frames of picture in the fingerprint recognition stage is relatively high, so that the brightness of the first few frames of picture is relatively large. It should be noted that the reasons for causing the phenomenon that the brightness of the first frame of picture in the fingerprint recognition stage is relatively large are not limited to the above-mentioned reasons, but can also be other reasons, which are not specifically exemplified herein.

[0048] In order to solve the problem of the brightness of the first several frames being too large in the fingerprint identification stage, the fingerprint identification stage is set to include a brightness compensation stage and a non-compensation stage in the embodiment. The brightness compensation stage includes at least one scanning frame, and the non-compensation stage includes at least one scanning frame. Parasitic capacitance and leakage and other factors have a large impact on the brightness of the frame in the early stage of the fingerprint identification stage, resulting in the brightness of the frame being too high. Therefore, the brightness compensation stage is located in the early stage of the fingerprint identification stage, and is used to adjust the brightness of the first several frames in the fingerprint identification stage, specifically to reduce the brightness of the first several frames in the fingerprint identification stage. With the increase of the frame number, the impact of parasitic capacitance and leakage and other factors on the brightness of the frame decreases. Therefore, the non-compensation stage is after the brightness compensation stage, and the impact of parasitic capacitance and leakage and other factors on the brightness of the frame in this stage is very small, and there is no need to adjust the brightness. The brightness of the first several frames in the early stage of the fingerprint identification stage is adjusted by setting the brightness compensation stage, so as to reduce the brightness of the first several frames in the fingerprint identification stage. This can reduce the brightness difference between the sub-frames in the fingerprint identification stage, and improve the fingerprint imaging quality.

[0049] In the brightness compensation stage, the output end of the compensation control unit 15 provides a first electrical signal, and different first electrical signals are provided for at least two scanning frames. In the non-compensation stage, the output end of the compensation control unit 15 provides a second electrical signal. The first electrical signal provided by the output end of the compensation control unit 15 in the brightness compensation stage is different from the second electrical signal provided in the non-compensation stage. The compensation control unit 15 provides different first electrical signals in the brightness compensation stage, which can adaptively adjust the fingerprint identification signal of the fingerprint identification circuit 16, and further realize the brightness adjustment of the sub-frames formed in the brightness compensation stage. This can reduce the brightness difference between the sub-frames in the fingerprint identification stage, and improve the fingerprint imaging quality.

[0050] As described above, the signal provided by the first signal end V1 changes, which will affect the potential of the first node N1. The potential of the first node N1 changes, which will affect the on-off state of the driving unit 13, and further affect the leakage current of the driving unit 13. The leakage current of the second node N2 changes, which will affect the potential of the signal output end OUT. Therefore, the signal provided by the first signal end V1 changes, which will affect the size of the fingerprint identification signal output by the signal output end OUT. In a scanning frame, the fingerprint identification module forms a sub-frame according to the fingerprint identification signal output by each fingerprint identification circuit 16. The change of the fingerprint identification signal output by the signal output end OUT will affect the brightness of the sub-frame. Specifically, the signal provided by the first signal end V1 decreases, which will reduce the fingerprint identification signal output by the signal output end OUT, and further reduce the brightness of the sub-frame. Based on this, the first electrical signal is designed to be smaller than the second electrical signal, which can reduce the brightness of the sub-frames in the brightness compensation stage, and reduce the difference between the brightness of the sub-frames in the brightness compensation stage and the brightness of the sub-frames in the non-compensation stage in the fingerprint identification stage.

[0051] Based on this, the output end of the compensation control unit 15 is connected to the first signal end V1, and the compensation control unit 15 provides different first electric signals to the first signal end V1 in the brightness compensation stage, so that the size of the fingerprint identification signal of the fingerprint identification circuit 16 can be adaptively adjusted, and then the brightness of the sub-frame picture formed in the brightness compensation stage is adjusted, the brightness difference between the sub-frame picture formed in the brightness compensation stage and the sub-frame picture formed in the non-compensation stage is reduced, and the imaging quality and the fingerprint identification accuracy are improved. The brightness of the sub-frame picture in the non-compensation stage tends to be stable, and based on this, the compensation control unit 15 provides a stable second electric signal to the first signal end V1 in the non-compensation stage, so that the brightness difference of the sub-frame picture formed in the non-compensation stage can be balanced. Finally, the imaging quality and the fingerprint identification accuracy are improved.

[0052] It should be noted that the brightness compensation stage includes the first to K-th frame scanning pictures, and the value of K can be measured in the laboratory. The value of K under different scanning frequencies can be different, and is not specifically limited. For example, the staff detects that under a scanning frequency of 60 Hz, the brightness of the first 5 frame pictures in the fingerprint identification stage decreases from large to small, and the brightness of the picture tends to be stable after the 6th frame picture, and the brightness difference between adjacent frame pictures is very small, so K can be set to 5 or slightly greater than 5; or the staff detects that under a scanning frequency of 120 Hz, the brightness of the first 12 frame pictures in the fingerprint identification stage decreases from large to small, and the brightness of the picture tends to be stable after the 13th frame picture, and the brightness difference between adjacent frame pictures is very small, so K can be set to 12 or slightly greater than 12.

[0053] It should be noted that the first signal end V1 provides a voltage signal to the fingerprint identification circuit 16, so when the signal adjustment end is the first signal end V1, the first electric signal and the second electric signal provided by the compensation control unit 15 are both voltage signals, and the compensation control unit 15 is a voltage controller for providing different voltage signals to the first signal end V1. Optionally, the signal adjustment end is the first signal end V1, and the compensation control unit 15 includes a voltage controller, and the output end of the voltage controller is connected to the signal adjustment end; the first electric signal provided by the voltage controller is a first voltage signal, and the second electric signal provided by the voltage controller is a second voltage signal. The structure of the voltage controller is not specifically described, and any voltage controller for providing an adjustable voltage signal falls within the protection scope of the present application.

[0054] In this embodiment of the invention, the fingerprint recognition circuit includes a compensation control unit. The output terminal of the compensation control unit is connected to a signal conditioning terminal, which can be a first signal terminal, a third signal terminal, or a signal output terminal. The fingerprint recognition stage includes a brightness compensation stage and a non-compensation stage. In the brightness compensation stage, the output terminal of the compensation control unit provides a first electrical signal and provides different first electrical signals to at least two scanned frames. In the non-compensation stage, the output terminal of the compensation control unit provides a second electrical signal. By providing different first electrical signals to the signal conditioning terminal in the brightness compensation stage, the compensation control unit can adaptively adjust the magnitude of the fingerprint recognition signal of the fingerprint recognition circuit, thereby adjusting the brightness of the sub-frames formed in the brightness compensation stage, reducing the brightness difference between the sub-frames formed in the brightness compensation stage and the non-compensation stage, making the brightness of each sub-frame in the fingerprint recognition stage more consistent, and improving the imaging quality and fingerprint recognition accuracy.

[0055] Figure 3 This is a schematic diagram of another fingerprint recognition circuit provided in an embodiment of the present invention. Figure 3 As shown, the output terminal of the compensation control unit 15 is connected to the signal conditioning terminal, which is the third signal terminal V3. The same structures as those in the above embodiments are represented by the same reference numerals in the accompanying drawings.

[0056] In this embodiment, a change in the signal provided by the third signal terminal V3 will affect the leakage current of the driving unit 13; a change in the leakage current of the second node N2 will affect the potential of the signal output terminal OUT. Therefore, a change in the signal provided by the third signal terminal V3 will affect the magnitude of the fingerprint recognition signal output by the signal output terminal OUT. In a scanned frame, the fingerprint recognition module forms a sub-frame based on the fingerprint recognition signals output by each fingerprint recognition circuit 16. A change in the fingerprint recognition signal output by the signal output terminal OUT will affect the brightness of that sub-frame. Specifically, a decrease in the signal provided by the third signal terminal V3 will reduce the fingerprint recognition signal output by the signal output terminal OUT, thereby reducing the brightness of the sub-frame.

[0057] Based on this, the output of the compensation control unit 15 is connected to the third signal terminal V3. During the brightness compensation phase, the compensation control unit 15 provides different first electrical signals to the third signal terminal V3, which can adaptively adjust the magnitude of the fingerprint recognition signal from the fingerprint recognition circuit 16. This allows for brightness adjustment of the sub-frame images formed during the brightness compensation phase, reducing the brightness difference between the sub-frame images formed during the brightness compensation phase and those formed in the non-compensation phase. During the non-compensation phase, the brightness of the sub-frame images tends to stabilize. The compensation control unit 15 then provides a stable second electrical signal to the third signal terminal V3 during the non-compensation phase, which can balance the brightness differences of the sub-frame images formed during the non-compensation phase. Ultimately, this improves image quality and fingerprint recognition accuracy.

[0058] It should be noted that the third signal end V3 provides a voltage signal for the fingerprint identification circuit 16, and therefore when the signal adjusting end is the third signal end V3, the first electric signal and the second electric signal provided by the compensation control unit 15 are both voltage signals, and the compensation control unit 15 is a voltage controller configured to provide different voltage signals for the third signal end V3. Optionally, the signal adjusting end is the third signal end V3, and the compensation control unit 15 includes a voltage controller, and the output end of the voltage controller is connected to the signal adjusting end; the first electric signal provided by the voltage controller is a first voltage signal, and the second electric signal provided by the voltage controller is a second voltage signal.

[0059] Figure 4 is another schematic diagram of the fingerprint identification circuit provided by the embodiment of the present application. As shown in the figure, the output end of the compensation control unit 15 is connected to the signal adjusting end, and the signal adjusting end is the signal output end OUT. In this embodiment, the same structure as in the above embodiments is marked with the same reference numerals. Figure 4

[0060] In this embodiment, in a frame of scanning picture, the fingerprint identification module forms a subframe picture according to the fingerprint identification signals output by the fingerprint identification circuit 16, and if the fingerprint identification signal output by the signal output end OUT changes, the brightness of the subframe picture will be affected. Specifically, if the fingerprint identification signal output by the signal output end OUT decreases, the brightness of the subframe picture will decrease.

[0061] Therefore, the output end of the compensation control unit 15 is directly connected to the signal output end OUT, and the compensation control unit 15 provides different first electric signals for the signal output end OUT in the brightness compensation stage, so as to adaptively adjust the size of the fingerprint identification signal of the fingerprint identification circuit 16, and further realize brightness adjustment of the subframe picture formed in the brightness compensation stage, and reduce the brightness difference between the subframe picture formed in the brightness compensation stage and the subframe picture formed in the non-compensation stage. The brightness of the subframe picture in the non-compensation stage tends to be stable, and the compensation control unit 15 provides a stable second electric signal for the signal output end OUT in the non-compensation stage, so as to balance the brightness difference of the subframe picture formed in the non-compensation stage. Finally, the imaging quality and the fingerprint identification accuracy are improved.

[0062] ​It should be noted that the fingerprint identification signal output by the fingerprint identification circuit 16 through the signal output terminal OUT is a current signal, therefore when the signal adjusting terminal is the signal output terminal OUT, the first electric signal and the second electric signal provided by the compensation control unit 15 are both current signals, then the compensation control unit 15 is a current controller, which is used to provide different current signals to the signal output terminal OUT. Alternatively, the signal adjusting terminal is the signal output terminal OUT, and the compensation control unit 15 comprises a current controller, the output terminal of the current controller is connected with the signal output terminal, the first electric signal provided by the current controller is a first current signal, and the second electric signal provided by the current controller is a second current signal.

[0063] Figure 5 is another schematic diagram of the fingerprint identification circuit provided by the embodiment of the present application. As shown in the figure, Figure 5 the first signal terminal V1 is alternatively multiplexed as the third signal terminal V3. In the embodiment, the same structure as the above-mentioned embodiments is marked with the same reference signs.

[0064] In the embodiment, the signal provided by the first signal terminal V1 changes, which will affect the potential of the first node N1; the potential of the first node N1 changes, which will affect the on-off state of the driving unit 13; the on-off state of the driving unit 13 and the change of the signal provided by the first signal terminal V1 will affect the drain current of the driving unit 13; the change of the drain current of the second node N2 will affect the potential of the signal output terminal OUT. Therefore, the change of the signal provided by the first signal terminal V1 will affect the size of the fingerprint identification signal output by the signal output terminal OUT. In a frame of scanning picture, the fingerprint identification module forms a sub-frame picture according to the fingerprint identification signal output by each fingerprint identification circuit 16, and the change of the fingerprint identification signal output by the signal output terminal OUT will affect the brightness of the sub-frame picture.

[0065] Based on this, the output terminal of the compensation control unit 15 is directly connected with the first signal terminal V1, the compensation control unit 15 provides different first electric signals to the first signal terminal V1 in the brightness compensation stage, which can adaptively adjust the size of the fingerprint identification signal of the fingerprint identification circuit 16, and then realize the brightness adjustment of the sub-frame picture formed in the brightness compensation stage, reduce the brightness difference between the sub-frame picture formed in the brightness compensation stage and the sub-frame picture formed in the non-compensation stage, and improve the imaging quality and the fingerprint identification precision. The brightness of the sub-frame picture in the non-compensation stage tends to be stable, based on this, the compensation control unit 15 provides a stable second electric signal to the first signal terminal V1 in the non-compensation stage, which can balance the brightness difference of the sub-frame picture formed in the non-compensation stage. Finally, the imaging quality and the fingerprint identification precision are improved. In other embodiments, the output terminal of the compensation control unit can also be directly connected with the signal output terminal.

[0066] Figure 6 isFigure 5 The timing diagram of the fingerprint identification circuit is shown. In this embodiment, the output end of the compensation control unit 15 is connected to the first signal end V1 as an example.

[0067] In combination Figure 2 And Figure 6 As shown, the STV_RST provides a reset trigger signal to the fingerprint identification module. If the reset trigger signal provided by the STV_RST is a valid trigger signal, the first row of the fingerprint identification circuit 16 in the fingerprint identification area 10 can be triggered to reset, and the shift is triggered to make the first row to the last row of the fingerprint identification circuit 16 reset at different times. The STV_READ provides a read trigger signal to the fingerprint identification module. If the read trigger signal provided by the STV_READ is a valid trigger signal, the first row of the fingerprint identification circuit 16 in the fingerprint identification area 10 can be triggered to read, and the shift is triggered to make the first row to the last row of the fingerprint identification circuit 16 read the fingerprint identification signal at different times. If the STV_RST provides a valid trigger signal to the fingerprint identification module, and the STV_READ provides a valid trigger signal to the fingerprint identification module, the fingerprint identification module opens a frame of scanning picture. Based on this, the time interval between the adjacent two valid trigger signals of the STV_RST can be defined as the time interval of the adjacent two frames of scanning picture, or the time interval between the adjacent two valid trigger signals of the STV_READ can be defined as the time interval of the adjacent two frames of scanning picture.

[0068] As Figure 6 shown, taking the high level of the valid trigger signal of the STV_RST and the STV_READ as an example, the STV_RST and the STV_READ can synchronously provide high level signal to make the fingerprint identification module open a frame of scanning picture. In a frame of scanning picture, the multiple rows of the fingerprint identification circuit 16 in the fingerprint identification area 10 output the fingerprint identification signal at different times. Among them, the same row of the fingerprint identification circuit 16 can synchronously output the fingerprint identification signal, and the different rows of the fingerprint identification circuit 16 can output the fingerprint identification signal at different times.

[0069] CK_C2, XCK_C2, CK_C1 and XCK_C1 all provide high and low level alternating control signals. Optionally, CK_C2 provides switch control signals to the switch control end C2 of the odd row fingerprint recognition circuit 16 in the fingerprint recognition area 10, and XCK_C2 provides switch control signals to the switch control end C2 of the even row fingerprint recognition circuit 16 in the fingerprint recognition area 10; optionally, CK_C1 provides reset control signals to the reset control end C1 of the odd row fingerprint recognition circuit 16 in the fingerprint recognition area 10, and XCK_C1 provides reset control signals to the reset control end C1 of the even row fingerprint recognition circuit 16 in the fingerprint recognition area 10. Taking the high level as an effective control signal as an example, when the reset control end C1 of the fingerprint recognition circuit 16 receives a high level signal, the reset unit 11 is controlled to be turned on, thereby realizing the reset of the first node N1; when the switch control end C2 of the fingerprint recognition circuit 16 receives a high level signal, the switch unit 14 is controlled to be turned on, thereby enabling the signal output end OUT to output the fingerprint recognition signal. The first signal end V1 receives a fixed potential signal in a frame of scanning picture.

[0070] Optionally, in the brightness compensation stage, the compensation control unit 15 provides the first electrical signal with step change to the continuous n frames of scanning pictures, and n is greater than or equal to 2. The second electrical signal and the first electrical signal with step change are stored in the compensation control unit 15 in advance, and then in the brightness compensation stage, the compensation control unit 15 provides the first electrical signal with step change to the first signal end V1, so that the size of the fingerprint recognition signal of the fingerprint recognition circuit 16 can be flexibly adjusted. In the non-compensation stage, the compensation control unit 15 provides the second electrical signal to the first signal end V1, and the influence of parasitic capacitance and leakage on the brightness of the sub-frame picture in this stage is very small, so that there is no need to adjust the brightness. Therefore, the second electrical signal is the electrical signal of the first signal end V1 in the ideal state. In this way, the brightness of the sub-frame picture formed in the brightness compensation stage can be adjusted, the brightness difference between the sub-frame pictures in the fingerprint recognition stage is reduced, and the imaging quality and the fingerprint recognition accuracy are improved.

[0071] Optionally, in the brightness compensation stage, the compensation control unit provides the first electrical signal with step increase to the continuous n frames of scanning pictures, and n is greater than or equal to 2. The existing fingerprint imaging detection finds that in the fingerprint recognition stage, the brightness of the first frame of picture is relatively large, and with the increase of the frame number, the brightness of the picture decreases until it reaches a stable state. Based on this, the first electrical signal provided by the compensation control unit 15 to the first signal end V1 in the first frame of scanning picture is relatively small, so as to reduce the brightness of the sub-frame picture formed thereby; with the increase of the frame number, the influence of parasitic capacitance and leakage on the brightness of the sub-frame picture is reduced, and therefore the compensation control unit 15 provides the first electrical signal with step increase to the multiple frames of scanning pictures, so as to adjust the brightness of the sub-frame picture formed thereby, and reduce the brightness difference between the adjacent sub-frame pictures. For example, it is found that the sub-frame picture brightness is stable after the fifth frame of scanning picture, and therefore the compensation control unit 15 provides the first electrical signal with step increase to the sixth frame of scanning picture, so as to reduce the brightness difference between the fifth and sixth frames of scanning pictures. Figure 6As shown, during the fingerprint recognition stage, in the first frame of the scan frame-1, the compensation control unit 15 provides the first electrical signal V to the first signal terminal V1. 11 In frame 2 of the second scan, the first electrical signal provided by the compensation control unit 15 to the first signal terminal V1 is V. 12 In frame 3 of the scan, the first electrical signal provided by the compensation control unit 15 to the first signal terminal V1 is V. 13 In frame 4 of the scan, the first electrical signal provided by the compensation control unit 15 to the first signal terminal V1 is V. 14 In the fifth frame of the scan and subsequent frames, the compensation control unit 15 provides the second electrical signal V to the first signal terminal V1. 10 Among them, V 11 <V 12 <V 13 V 13 <V 14 <V 10 As the frame rate increases, the compensation control unit 15 provides a first electrical signal with a stepped increase to the multi-frame scan image, thereby reducing the brightness of the resulting sub-frame images until the brightness difference between the sub-frame images is very small. After that, the compensation control unit 15 provides a stable second electrical signal to the multi-frame scan image.

[0072] Optionally, during the brightness compensation phase, the compensation control unit provides a first electrical signal V to the (i-1)th frame of the scanned image. i-1 The compensation control unit provides the first electrical signal V to the i-th scanned frame. i The compensation control unit provides the first electrical signal V to the (i+1)th frame of the scanned image. i+1 Among them, V i -V i-1 ≥V i+1 -V i where i is a positive integer. For example, such as... Figure 6 As shown, in the fingerprint recognition stage, in the first frame of the scan frame-1, the first electrical signal is V. 11 In frame 2 of the second scan, the first electrical signal is V. 12 In frame 3 of the scanned image, the first electrical signal is V. 13 In frame 4 of the 4th scan, the first electrical signal is V. 14As the frame rate increases, the impact of factors such as parasitic capacitance and leakage current on image brightness decreases. Based on this, the first electrical signal of the first few frames is designed to increase from small to large, and the difference between the first electrical signals of the first few frames is also designed to decrease from large to small. Therefore, as the frame rate increases, the difference between the first electrical signals of each frame decreases, allowing the first electrical signal to approach the second electrical signal. V can be selected as the first electrical signal. 12 -V 11 ≥V 13 -V 12 ≥V 14 -V 13 As the frame rate increases, the first electrical signal V of each subsequent frame stabilizes. 10 .

[0073] Figure 7 This is a schematic diagram of another fingerprint recognition circuit provided in an embodiment of the present invention. Figure 7 As shown, taking the multiplexing of the first signal terminal V1 as the third signal terminal V3 as an example, the same structures as in the above embodiments are represented by the same reference numerals. Optional reset unit 11 includes a reset transistor M1 connected between the first signal terminal V1 and the first node N1, with its gate connected to the reset control terminal C1; drive unit 13 includes a drive transistor M2 connected between the third signal terminal V3 and the second node N2, with its gate connected to the first node N1; switch unit 14 includes a switch transistor M3 connected between the second node N2 and the signal output terminal OUT, with its gate connected to the switch control terminal C2. Each transistor can be an NMOS, but is not limited to this. Optional compensation control unit 15 is connected to the first signal terminal V1.

[0074] Combination Figure 6 As shown, the operation of the fingerprint recognition circuit includes a reset phase and a reading phase. A portion of the reading phase is reused as the reset phase.

[0075] During the reset phase, the reset control terminal C1 provides a high-level signal to turn on the reset transistor M1, the switch control terminal C2 provides a high-level signal to turn on the switch transistor M3, and the compensation control unit 15 provides an electrical signal to the first signal terminal V1 to reset the first node N1. During the brightness compensation phase, the compensation control unit 15 provides a first electrical signal to the first signal terminal V1 to reset the first node N1; during the non-compensation phase, the compensation control unit 15 provides a second electrical signal to the first signal terminal V1 to reset the first node N1.

[0076] In the reading stage, the switch control end C2 provides a high level signal to turn on the switch transistor M3, the signal of the third signal end V3 flows through the drive transistor M2 and the switch transistor M3, and the fingerprint identification signal is output through the signal output end OUT. In the brightness compensation stage, the compensation control unit 15 provides the first electric signal to the third signal end V3; in the non-compensation stage, the compensation control unit 15 provides the second electric signal to the third signal end V3.

[0077] At least one of the optional reset transistor and the switch transistor is a double-gate transistor. As shown in the figure, Figure 7 the reset transistor M1 and the switch transistor M3 are both double-gate transistors. The double-gate transistor has a smaller drain current, which can reduce the interference on the fingerprint identification signal output by the signal output end OUT and improve the fingerprint identification accuracy.

[0078] Figure 8 is another schematic diagram of the fingerprint identification circuit provided by the embodiment of the present application. As shown in the figure, Figure 8 the optional reset unit 11 includes the reset transistor M1 connected between the first signal end V1 and the first node N1, and the gate of the reset transistor M1 is connected to the reset control end C1; the drive unit 13 includes the drive transistor M2 connected between the third signal end V3 and the second node N2, and the gate of the drive transistor M2 is connected to the first node N1; the switch unit 14 includes the switch transistor M3 connected between the second node N2 and the signal output end OUT, and the gate of the switch transistor M3 is connected to the switch control end C2. Optionally, each transistor is an NMOS, but is not limited thereto. Optionally, the compensation control unit 15 is connected to the signal output end OUT.

[0079] In the brightness compensation stage, the compensation control unit 15 provides the first electric signal to the signal output end OUT to adjust the size of the fingerprint identification signal, so as to adjust the brightness of the sub-frame picture; in the non-compensation stage, the compensation control unit 15 provides the stable second electric signal to the signal output end OUT.

[0080] At least one of the optional reset transistor and the switch transistor is a double-gate transistor. As shown in the figure, Figure 8 the reset transistor M1 and the switch transistor M3 are both double-gate transistors. The double-gate transistor has a smaller drain current, which can reduce the interference on the fingerprint identification signal output by the signal output end OUT and improve the fingerprint identification accuracy.

[0081] Figure 9 is another schematic diagram of the fingerprint identification circuit provided by the embodiment of the present application. As shown in the figure, Figure 9As shown, the optional compensation control unit 15 comprises a current controller; the current controller comprises a first resistor R1, a second resistor R2, a first capacitor Cs and a constant current source A1; a first end of the first resistor R1 is connected to the signal output end OUT, and a second end of the first resistor R1 is respectively connected to a first end of the second resistor R2 and a first end of the constant current source A1; a second end of the second resistor R2 is grounded GND through the first capacitor Cs, and a second end of the constant current source A1 is grounded GND.

[0082] It should be noted that the fingerprint identification signal output by the fingerprint identification circuit 16 through the signal output end OUT is a current signal, therefore, when the signal adjustment end is the signal output end OUT, the first electric signal and the second electric signal provided by the compensation control unit 15 are both current signals, then the compensation control unit 15 is a current controller, which is used to provide different current signals to the signal output end OUT. The structure of the current controller can be as shown in Figure 9 but is not limited thereto, and any current controller used to provide adjustable current signals falls within the protection scope of the present application.

[0083] Based on the same inventive concept, the present application also provides a compensation method, which is applied to the fingerprint identification circuit as described in any of the above embodiments. The compensation method can be realized by a compensation device, which can be configured in an electronic device integrated with a fingerprint identification function. Figure 10 is a schematic diagram of a compensation method provided by the present application. As shown in Figure 10 the compensation method comprises:

[0084] Step 110, detecting whether the time difference between the starting moment of the current frame of scanning pictures and the starting moment of the previous frame of scanning pictures is greater than a first scanning time length;

[0085] Step 120, if yes, entering a brightness compensation stage, in which the output end of the compensation control unit is controlled to provide the first electric signal, and different first electric signals are provided to at least two frames of scanning pictures.

[0086] The optional compensation method further comprises: Step 130, if no, controlling the output end of the compensation control unit to provide the second electric signal in a non-compensation stage.

[0087] In combination with Figure 6 As shown, the compensation device provides an effective trigger signal to the fingerprint identification module through the STV_RST, and provides an effective trigger signal to the fingerprint identification module through the STV_READ, then the fingerprint identification module starts a frame of scanning pictures. Based on this, the compensation device can determine the time interval between the adjacent two effective trigger signals of the STV_RST as the time interval of the adjacent two frames of scanning pictures, or determine the time interval between the adjacent two effective trigger signals of the STV_READ as the time interval of the adjacent two frames of scanning pictures.Figure 6 The time difference between the starting time of the current frame of scanning picture and the starting time of the previous frame of scanning picture is the time interval between the effective trigger signals provided by the STV_RST to the fingerprint identification module. The starting time of a frame of scanning picture is the starting time of the first row of scanning of the frame of scanning picture. It can be understood that the fingerprint identification stage is composed of a plurality of continuous frames of scanning picture, and the time interval between the starting times of the adjacent two frames of scanning picture in the fingerprint identification stage is fixed or close.

[0088] If the STV_RST outputs the invalid trigger signal after the previous frame of scanning picture is completed, and the STV_RST outputs the effective trigger signal to start the current frame of scanning picture after a long time interval, the compensation device can determine that the time interval between the starting time of the previous frame of scanning picture and the starting time of the current frame of scanning picture is large according to the time interval between the adjacent two effective trigger signals of the STV_RST. Based on this, the compensation device can define the previous frame of scanning picture as the last frame of scanning picture of the previous fingerprint identification stage, and define the current frame of scanning picture as the first frame of scanning picture of the new fingerprint identification stage. In the current fingerprint identification stage, the brightness of the first few frames of scanning picture is larger due to the influence of the parasitic capacitance and the leakage, and the compensation device controls the brightness compensation.

[0089] In the embodiment, the compensation device determines whether to start a new fingerprint identification stage by judging the time difference between the starting times of the adjacent two frames of scanning picture. If the time difference between the starting times of the adjacent two frames of scanning picture is too large, it is determined to start a new fingerprint identification stage, and in the current fingerprint identification stage, the brightness compensation stage is controlled to be executed before the non-compensation stage, so as to realize the brightness adjustment of the first few frames of scanning picture in the new fingerprint identification stage. It can be understood that the compensation device can be a driving chip in the electronic device, which directly or indirectly provides corresponding signals to the reset control end, the switch control end, the first signal end, the second signal end and the third signal end of the fingerprint identification circuit, and obtains the fingerprint identification signal of the fingerprint identification circuit through the signal output end.

[0090] The first scanning time is preset in the compensation device, and the first scanning time can be the sum of the scanning times of two frames of scanning picture, but is not limited thereto. Those skilled in the art can reasonably design the first scanning time according to the needs of the product, for example, the first scanning time can be the sum of the scanning times of 10 frames of scanning picture.

[0091] The compensation device detects a time interval between two adjacent effective trigger signals of the STV_RST (or STV_READ), which is a time difference between a starting time of a current frame of scanning pictures and a starting time of a previous frame of scanning pictures. After the time difference is detected, the compensation device determines whether the time difference is greater than a first scanning time. If the time difference is greater than the first scanning time, it indicates that the time difference between the starting time of the current frame of scanning pictures and the starting time of the previous frame of scanning pictures is too large, and the current frame of scanning pictures is a first frame of scanning pictures in a new fingerprint identification stage. Then, the compensation device controls the fingerprint identification circuit to enter a brightness compensation stage, controls the output end of the compensation control unit to provide a first electric signal in the stage, and provides different first electric signals to at least two frames of scanning pictures. If the time difference is less than or equal to the first scanning time, it indicates that the time difference between the starting time of the current frame of scanning pictures and the starting time of the previous frame of scanning pictures is small, and the current frame of scanning pictures and the previous frame of scanning pictures can be determined as the same fingerprint identification stage. Then, the compensation device controls the output end of the compensation control unit to provide a second electric signal in a non-compensation stage.

[0092] Optionally, the control of the output end of the compensation control unit to provide different first electric signals to at least two frames of scanning pictures includes: in the brightness compensation stage, the output end of the compensation control unit is controlled to provide an i-order first electric signal to an i-th frame of scanning pictures, and the i-order first electric signal is less than an (i+x)-order first electric signal, i is a positive integer, and x is greater than or equal to 1. In the brightness compensation stage, as the number of frames increases, the influence of the parasitic capacitance and the leakage on the brightness of the sub-frame picture decreases, so the output end of the compensation control unit provides an electric signal with a gradually increasing step to the signal adjusting end, so that the first electric signal gradually approaches the second electric signal as the number of frames increases, and then the brightness of the sub-frame picture in the brightness compensation stage gradually decreases and approaches the brightness of the sub-frame picture in the non-compensation stage. The (i+x)-th frame of scanning pictures provides the (i+x)-order first electric signal.

[0093] Optionally, the compensation control unit includes a current controller, and an output end of the current controller is connected to the signal output end. The first electric signal provided by the current controller is a first current signal, and the second electric signal provided by the current controller is a second current signal. Optionally, the output end of the current controller provides a current signal with high and low levels alternately, and the high level of the first current signal is less than the high level of the second current signal. In this embodiment, the output current of the current controller is set to a step mode varying with the number of frames, and the signal fluctuation corresponding to the problem of the first frame brightness being too large in the fingerprint identification stage is compensated. In other embodiments, the compensation control unit includes a voltage controller, and the output voltage of the voltage controller is set to a step mode varying with the number of frames, and the signal fluctuation corresponding to the problem of the first frame brightness being too large in the fingerprint identification stage is compensated.

[0094] Figure 11 is Figure 8The timing diagram of the fingerprint identification circuit is shown. In this embodiment, the output end of the compensation control unit 15 is connected to the signal output end OUT as an example. The compensation control unit 15 includes a current controller. The output end of the current controller provides a current signal Iout to the signal output end OUT, and the current signal Iout includes a constant current signal in 1 frame. The current controller provides a stable current signal Iout to the signal output end OUT, which can make the brightness compensation more uniform and the brightness adjustment more flexible.

[0095] When the fingerprint identification circuit is working, the driving transistor M2 works in the saturation region, so the following formula is met: α(V q -V th -V s ) 2 =I, V s -V out =I*R M3 , and thus wherein V q represents the gate voltage of the driving transistor M2, V th represents the threshold voltage of the driving transistor M2, V s represents the source voltage of the driving transistor M2, I represents the output current of the current controller, V OUT represents the voltage of the signal output end OUT, and R M3 represents the on-state resistance of the switching transistor M3. According to the correlation between the fingerprint identification signal and the current controller output signal, the first frame brightness problem in the fingerprint identification stage can be improved by the current compensation method. Based on this, the current signal Iout output by the current controller in the brightness compensation stage can be increased step by step with the increase of the frame number, wherein the current signal of the first frame is I 11 , the current signal of the second frame is I 12 , the current signal of the third frame is I 13 , the current signal of the fourth frame is I 14 , and the fifth frame enters the non-compensation stage, and the current signal of the fifth frame is I 10 . Wherein I 11 ≤I 12 ≤I 13 ≤I 14 ≤I 10 .

[0096] Figure 12 is Figure 8Another timing diagram of the fingerprint identification circuit is shown. In this embodiment, the output end of the compensation control unit 15 is connected to the signal output end OUT. The compensation control unit 15 includes a current controller. The output end of the current controller provides a current signal Iout to the signal output end OUT, and the current signal Iout includes a current signal with high and low levels alternately in one frame. The current controller provides the signal output end OUT with the current signal Iout with high and low levels alternately, so that power consumption can be saved.

[0097] When the fingerprint identification circuit is working, the driving transistor M2 works in the saturation region, so the following formula is met: α(V q -V th -V s ) 2 =I, V s -V out =I*R M3 , so wherein V q represents the gate voltage of the driving transistor M2, V th represents the threshold voltage of the driving transistor M2, V s represents the source voltage of the driving transistor M2, I represents the output current of the current controller, V OUT represents the voltage of the signal output end OUT, and R M3 represents the on-state resistance of the switching transistor M3. According to the correlation between the fingerprint identification signal and the output signal of the current controller, the first frame brightness problem in the fingerprint identification stage can be improved by the current compensation method. Based on this, the high level of the current signal Iout output by the current controller in the brightness compensation stage can be increased step by step with the increase of the frame number, wherein the high level of the current signal of the first frame is I 21 , the high level of the current signal of the second frame is I 22 , the high level of the current signal of the third frame is I 23 , the high level of the current signal of the fourth frame is I 24 , and the fifth frame enters the non-compensation stage, and the high level of the current signal of the fifth frame is I 20 . Wherein I 21 ≤I 22 ≤I 23 ≤I 24 ≤I 20 .

[0098] Based on the same inventive concept, the embodiment of the present application also provides a display panel, which includes the fingerprint identification circuit described in any of the above embodiments.

[0099] In the embodiment, the display panel is provided with a fingerprint identification module, the fingerprint identification module drives a fingerprint identification circuit to perform a fingerprint identification function, the fingerprint identification module further includes other auxiliary structures, and the fingerprint identification module performs fingerprint identification imaging according to a fingerprint identification signal output by the fingerprint identification circuit. A local area of a display area of the display panel can be reused as a fingerprint identification area, one or more fingerprint identification areas can be included in the display area, based on which the display panel implements a local fingerprint identification function; or alternatively, a fingerprint identification area covers the display area of the display panel, based on which the display panel implements a full-screen fingerprint identification function.

[0100] The embodiment of the present application further provides a display device, which comprises the display panel as described in the above embodiment. Figure 13 is a schematic diagram of the display device provided by the embodiment of the present application. As shown in Figure 13 the optional display device 1 is a mobile phone, but in other embodiments, the optional display device can also be a tablet computer, a computer or other electronic equipment. The embodiment can be applied to any display device 1 integrated with a fingerprint identification function, such as an organic light-emitting display device with a fingerprint identification function. However, the type of the display device 1 is not limited thereto. In the embodiment, the display device 1 can adjust the first-frame brightness in the fingerprint identification stage by voltage regulation on the first signal terminal or the third signal terminal, or by current regulation on the signal output terminal, so as to improve the fingerprint imaging quality and the fingerprint identification accuracy.

[0101] The above specific embodiments do not constitute a limitation on the protection scope of the present application. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A fingerprint recognition circuit, characterized by, The application relates to a fingerprint identification circuit, which comprises a reset unit, a light sensing unit, a driving unit, a switching unit and a compensation control unit. The reset unit is connected between a first signal end and a first node, and a control end of the reset unit is connected to a reset control end. The light sensing unit is connected between a second signal end and the first node, and is used for sensing a light signal and generating a corresponding electric signal. The driving unit is connected between a third signal end and a second node, and a control end of the driving unit is connected to the first node. The switching unit is connected between the second node and a signal output end, and a control end of the switching unit is connected to a switching control end. An output end of the compensation control unit is connected to a signal adjusting end, and the signal adjusting end is the first signal end, the third signal end or the signal output end. In a fingerprint identification stage, the fingerprint identification circuit works. The fingerprint identification stage comprises multiple scanning pictures, and the fingerprint identification stage comprises a brightness compensation stage and a non-compensation stage, the brightness compensation stage comprises at least one scanning picture, and the non-compensation stage comprises at least one scanning picture. In the brightness compensation stage, an output end of the compensation control unit provides a first electric signal, and different first electric signals are provided for at least two scanning pictures. In the non-compensation stage, an output end of the compensation control unit provides a second electric signal. In the brightness compensation stage, the compensation control unit provides a first electric signal with step change for continuous n scanning pictures, and n is greater than or equal to 2.

2. The fingerprint recognition circuit of claim 1, wherein, In the brightness compensation stage, the compensation control unit provides a first electric signal with step increase for continuous n scanning pictures, and n is greater than or equal to 2.

3. The fingerprint recognition circuit of claim 1, wherein, The first signal end is multiplexed as the third signal end.

4. The fingerprint recognition circuit of claim 3, wherein, In the luminance compensation stage, the compensation control unit provides the (i-1)th frame of scanning picture with the first electric signal V i-1 , the compensation control unit provides the ith frame of scanning picture with the first electric signal V i , and the compensation control unit provides the (i+1)th frame of scanning picture with the first electric signal V i+1 . wherein V i -V i-1 ≥V i+1 -V i i is a positive integer.

5. The fingerprint recognition circuit of claim 1, wherein, The first electric signal is smaller than the second electric signal.

6. The fingerprint recognition circuit of claim 1, wherein, The signal adjusting end is the first signal end or the third signal end.

7. The fingerprint recognition circuit of claim 1, wherein, The compensation control unit comprises a voltage controller, and an output end of the voltage controller is connected to the signal adjusting end. The first electric signal provided by the voltage controller is a first voltage signal, and the second electric signal provided by the voltage controller is a second voltage signal. The compensation control unit comprises a current controller, and an output end of the current controller is connected to the signal output end.

8. The fingerprint recognition circuit of claim 1, wherein, The first electric signal provided by the current controller is a first current signal, and the second electric signal provided by the current controller is a second current signal. The current controller comprises a first resistor, a second resistor, a first capacitor and a constant current source.

9. The fingerprint recognition circuit of claim 8, wherein, A first end of the first resistor is connected to the signal output end, and a second end of the first resistor is respectively connected to a first end of the second resistor and a first end of the constant current source. A second end of the second resistor is grounded through the first capacitor, and a second end of the constant current source is grounded. The reset unit comprises a reset transistor, the reset transistor is connected between the first signal end and the first node, and a gate of the reset transistor is connected to the reset control end.

10. The fingerprint recognition circuit of claim 1, wherein, The driving unit comprises a driving transistor, the driving transistor is connected between the third signal end and the second node, and a gate of the driving transistor is connected to the first node. ​ The switch unit comprises a switch transistor connected between the second node and the signal output terminal, and a gate of the switch transistor is connected to the switch control terminal.

11. The fingerprint recognition circuit of claim 10, wherein, At least one of the reset transistor and the switch transistor is a double-gate transistor.

12. A compensation method characterized by, The compensation method is applied to the fingerprint identification circuit of any one of claims 1-11, and the compensation method comprises: detecting whether a time difference between a starting time of a current frame of scanning picture and a starting time of a previous frame of scanning picture is greater than a first scanning time length; if yes, entering a brightness compensation stage, and in the stage, an output terminal of the compensation control unit is controlled to provide a first electric signal, and at least two frames of scanning pictures are provided with different first electric signals.

13. The compensation method according to claim 12, characterized in that, Further comprising: if no, in a non-compensation stage, the output terminal of the compensation control unit is controlled to provide a second electric signal.

14. The compensation method of claim 12, wherein, controlling the output terminal of the compensation control unit to provide different first electric signals for at least two frames of scanning pictures comprises: in the brightness compensation stage, the output terminal of the compensation control unit is controlled to provide an i-th order first electric signal for an i-th frame of scanning picture, and the i-th order first electric signal is smaller than an (i+x)-th order first electric signal, i is a positive integer, and x is greater than or equal to 1.

15. The compensation method according to claim 14, characterized in that, The compensation control unit comprises a current controller, and an output terminal of the current controller is connected to the signal output terminal. The first electric signal provided by the current controller is a first current signal, and the second electric signal provided by the current controller is a second current signal.

16. The compensation method of claim 15, wherein, The output terminal of the current controller provides a current signal with high and low levels alternately, wherein a high level of the first current signal is smaller than a high level of the second current signal.

17. A display panel, characterized by The fingerprint identification circuit of any one of claims 1-11.

18. A display device comprising: The display panel of claim 17.

Images